<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.js"></script>
</head>

<body>
    <div id="app">
        <p><input type="text" v-model="msg" @keyup.enter="handleEnter"> </p>
        <p v-for="item of arr" :key="item.id" @click="handleDelete(item)">{{item}}</p>
    </div>
    <script>
        new Vue({
            el: "#app",
            data: {
                msg: "hello",
                arr: []
            },
            methods: {
                handleEnter() {
                    var arr = this.arr
                    if (!arr.includes(this.msg)) {
                        this.arr.push(this.msg)
                    }else{
                        alert('数据已经存在')
                    }
                },
                handleDelete(val){
                    var arr = this.arr;
                    var index = arr.findIndex(item=>item==val);
                    console.log(index);
                    this.arr.splice(index,1)
                }
            },
        })
    </script>
</body>

</html>